The programs used to calibrate the hydrologic models are:

the manual calibration program (MCP) operates by applying hydrologic models with user-specified values for all parameters. the Interactive Calibration Program (ICP)) displays simulated and observed hydrographs and model states to enable rapid and visually oriented MCP runs, thus enhancing the calibration process. the automatic parameter optimizer (OPT) operates in a similar manner, but includes a procedure to automatically adjust parameter values to improve the streamflow simulation.

The calibration software is intended for use on just one segment of a river system at a time.
A major river system is calibrated a basin at a time, with a typical calibration run spanning multiple years of historical data.
In contrast, the Operational Forecast System operates on an entire river system, but for comparatively short time periods.